A sphincterotomy is a surgical procedure involving the cutting or incision of a sphincter, which is a ring-like muscle that naturally closes an opening in the body. This operation is performed to relieve high tension or blockage within the muscle, allowing for improved flow or healing of adjacent tissue. By partially dividing the muscle fibers, the procedure reduces the resting pressure of the sphincter. This muscle relaxation is intended to treat conditions where muscle spasm or narrowing prevents normal bodily function.
Why a Sphincterotomy is Needed
The need for a sphincterotomy arises in two distinct areas of the body, each involving a different type of muscular valve. In the gastrointestinal context, the procedure is most commonly used to treat chronic anal fissures. These are small tears in the lining of the anal canal that fail to heal because of excessive and prolonged spasm of the internal anal sphincter muscle.
Continuous tension in this involuntary muscle reduces blood flow, preventing the fissure from receiving the necessary resources to repair itself. By performing a lateral internal sphincterotomy (LIS), the resting pressure is lowered, often by 20% to 50%. This reduction in pressure increases blood circulation to the tear, allowing the chronic wound to finally heal.
The second application is within the digestive system, where the bile and pancreatic ducts drain into the small intestine. This opening is controlled by a muscular valve known as the sphincter of Oddi. Conditions like gallstones that have migrated into the common bile duct (choledocholithiasis) can become trapped, causing a blockage. This obstruction can lead to severe pain, jaundice, or inflammation of the pancreas (pancreatitis) or bile ducts (cholangitis). An endoscopic sphincterotomy (ES) is performed to widen the duct opening, allowing stones or sludge to pass naturally or enabling a physician to insert instruments to remove them.
How the Procedure is Performed
Lateral Internal Sphincterotomy (LIS)
Lateral internal sphincterotomy (LIS) is a minor surgical operation typically performed on an outpatient basis under general or regional anesthesia. The surgeon aims to cut only a small portion of the internal anal sphincter muscle, preserving the external anal sphincter responsible for voluntary bowel control. The procedure can be done using either an open or closed technique.
In the closed technique, a small incision is made near the anus, and a specialized scalpel divides the internal muscle fibers from within. The open technique involves a small radial incision across the intersphincteric groove; the muscle is then identified and divided using a scalpel or electrocautery. The goal is to divide the muscle up to a specific anatomical landmark called the dentate line to ensure sufficient pressure reduction without compromising continence. The operation often takes less than 30 minutes.
Endoscopic Sphincterotomy (ES)
The endoscopic sphincterotomy is a minimally invasive technique that occurs during a procedure called Endoscopic Retrograde Cholangiopancreatography (ERCP). The patient is sedated, and a flexible, lighted tube called an endoscope is passed through the mouth, down the esophagus and stomach, into the duodenum. The physician guides the endoscope to the papilla of Vater, the opening where the bile and pancreatic ducts meet.
A specialized catheter, the sphincterotome, is inserted through the working channel of the endoscope into the duct. The sphincterotome contains a thin wire that is positioned across the sphincter of Oddi muscle. An electrical current (electrocautery) is applied through the wire to make a controlled incision, widening the duct opening. This cut allows for the passage of stones, the insertion of stents for drainage, or other therapeutic maneuvers.
What to Expect During Recovery
Recovery from a sphincterotomy varies depending on whether the procedure was a surgical LIS or an endoscopic ES. For LIS, patients are released to go home the same day, though discomfort is expected for the first few days. Pain management involves prescription or over-the-counter medication; patients are encouraged to take sitz baths to soothe the area and promote circulation.
Most people feel well enough to return to light work and daily activities within one to two weeks. The surgical wound may take up to six weeks to fully heal. Maintaining a high-fiber diet and drinking plenty of fluids is recommended to prevent constipation and straining, which could impede the healing process.
The primary concern following LIS is the potential for minor, temporary fecal incontinence, which may manifest as difficulty controlling gas or stool leakage. While short-term incontinence is reported by some patients, it resolves for the majority as the muscle adapts to the change in tension. Long-term, persistent minor incontinence occurs in a small percentage of patients, estimated between 1.2% and 3.5%.
Recovery from endoscopic sphincterotomy (ES) is quicker, often requiring a short hospital stay of one to two days for observation. The most significant complication following ES is post-procedure pancreatitis, which occurs in 3% to 10% of patients. This inflammation can range from mild to severe; the risk is heightened if the sphincter of Oddi was dysfunctional or the procedure was technically challenging.
Other risks include bleeding, infection (cholangitis), and perforation of the duodenum; overall complication rates for ES are around 7%. Following a successful procedure, long-term results are positive, with a high success rate in resolving underlying issues like gallstone obstruction or sphincter dysfunction. However, late complications are possible, such as stone recurrence or the narrowing of the duct opening over time.